日: 2026年4月21日

How to Accurately Measure Higher-Order IMD Products Using a Spectrum Analyzer?

You see terrible intermodulation distortion1 (IMD) results on the screen, and they don’t match the datasheet. Is your expensive new amplifier a dud? It’s a frustrating and costly problem. To accurately measure IMD, you must use the spectrum analyzer’s internal attenuator. By increasing the input attenuation by 10 dB, check if the measured IMD products drop. If they drop by much more than 10 dB, they are being generated inside the analyzer, not by your device. I’ll never forget the time I was at a client’s lab. He pointed to the spectrum analyzer2 screen and told me, “Your amplifier’s IMD specs are not good.” I knew that amplifier was solid. […]